A collar B of mass `2kg` is constrained to move along a horizontal smooth and fixed circular track of radius `5m`. The spring lying in the plane of the circular track and having spring constant `200Nm^-1` is underformed when the collar is at A. If the collar starts from rest at B, the normal reaction exerted by the track on the collar when it passes through A is

Options

A. 360 N
B. 720 N
C. 1440 N
D. 2880 N

Answer

C

Explanation

From the third equation of motion, `v^(2) = u^(2) +2as implies 0=(50xx(5)/(18))^(2)+2axx6`
or `a=-16ms^(-2)" "(therefore" a is retardation")`
Again, `v^(2)=u^(2)+2as`
`implies 0=(100xx(5)/(18))^(2)-16xx2xxs" or "s=((100xx5)^(2))/(18xx18xx32)" or s = 24.1 = 24m"`